The goal of this proposal is to determine the role of the endogenous kappa opioid system in ethanol withdrawal seizures utilizing Withdrawal Seizure-Prone (WSP) mice which have been selectively bred for a severe ethanol withdrawal seizure phenotype. This goal will be accomplished by looking at transcription and translation of dynorphin, a kappa opioid receptor ligand, as well as the kappa opioid receptor itself in animals which have undergone 72 hours of chronic ethanol exposure with and without subsequent withdrawal. Specific sites of expression will be identified using in situ hybridization and immunocytochemistry; both global and site-specific regulation of dynorphin and the kappa opioid receptor will be determined. Specific areas identified to be regulated will be characterized in DBA/2J mice, an inbred line of mice which have not been selected for this phenotype but nevertheless exhibit similar seizures when withdrawn from ethanol. In addition, expression of the kappa opioid system will be studied in the Withdrawal Seizure-Resistant (WSR) mice in an attempt to further confirm the role of this system in ethanol withdrawal seizures and to determine whether alterations of this system are a correlated response to selection. Correlation between withdrawal seizure severity and the magnitude of kappa opioid system alterations will be examined to determine whether this system contributes to the severity of withdrawal seizures.